Dentistry's role in obstructive sleep apnoea. Review and case report.

Obstructive sleep apnoea (OSA) has been associated with many life-threatening conditions but has only recently appeared in the dental literature. Dental appliances and orthognathic surgery are two strategies which are currently used in the treatment of sleep apnoea. This article provides a background on OSA and these treatment approaches, and discusses the potential risks and benefits of each. A case is reported to illustrate the use of a dental appliance in the treatment of OSA.

Maxillomandibular advancement surgery in obstructive sleep apnea syndrome patients: long-term surgical stability.

PURPOSE: This study examined the long-term skeletal stability of relatively large maxillomandibular advancement surgery in the treatment of obstructive sleep apnea syndrome (OSAS). MATERIALS AND METHODS: The presurgical, immediate (< 1 month), and long-term (> 12 months) postsurgical cephalometric radiographs of 19 patients undergoing maxillomandibular advancement with simultaneous genioplasty for OSAS were studied. The cephalometric measurements and calculations were performed using a commercial cephalometric software. RESULTS: Maxillary and mandibular advancement seems to be stable in the horizontal and vertical planes over the long term. There was no significant correlation between the amount of surgical advancement and the amount of postsurgical instability, with the exception of gonion in the vertical plane. CONCLUSION: The results from this study indicate that large surgical advancements in OSAS patients result in relatively stable repositioning of the maxilla and mandible over the long term.

The validity of maxillary expansion indices.

Numerous indices have been proposed to help the clinician decide how much maxillary expansion will be required to alleviate crowding. The purpose of this investigation was to examine the validity of Pont's index, Schwarz's analysis and McNamara's rule of thumb. Records of 40 patients (20 females and 20 males) were selected from 155 consecutive pretreatment records. The discrepancy between actual intermolar/interpremolar widths and the index-generated widths were correlated against measures of crowding, and linear regressions were computed. Statistical analysis revealed that (1) males had more significant correlations between arch width and crowing than females, (2) interpremolar widths were more strongly correlated than intermolar widths, (3) Pont's index and McNamara's rule of thumb overestimated required arch width by 2.5 mm to 4.7 mm and 2.7 mm to 3.7 mm respectively, and (4) Schwarz's analysis overestimated interpremolar width by 2.5 mm to 4.3 mm but was reasonably accurate for intermolar width in males. The results suggest that these indices potentially overestimate the arch expansion required to alleviate crowding.

Reliability of computer-generated cephalometrics.

The use of computer-generated cephalometric analyses has gained popularity in both research and clinical applications. This study was conducted to determine the reliability of the computerized cephalometric methodology. A customized cephalometric analysis of 40 cephalometric radiographs was performed using 22 cephalometric landmarks to evaluate 40 measurements. Reproducibility studies were performed for each step of the computerized cephalometry used. The computer-generated measurements were also compared with those obtained through the conventional hand-measured method. The measurements obtained through the computerized methodology were reproducible for most parameters studied, although point B was found to be unreliable in the vertical plane. The combined errors from video imaging, digitization of the image, and the software were not methodologically significant. No statistically significant errors were found for the repeated measurements of the retrieved digital images. However, the absolute values of all parameters related to the horizontal plane from the computerized method were 0.7 to 1.0 mm greater than those from the conventional hand-measured method, indicating that some horizontal magnification occurred. This information is useful for the interpretation of data obtained from computerized cephalometry.

Maxillomandibular advancement surgery in patients with obstructive sleep apnea: mandibular morphology and stability.

Causal associations between various craniofacial morphologic variables and obstructive sleep apnea have been inferred and serve to justify many treatments. The purposes of this study were to examine the presurgical and postsurgical mandibular morphology of patients with obstructive sleep apnea who were undergoing maxillomandibular advancement and to assess the stability of the observed changes. Various mandibular morphologic variables of 32 male subjects were measured on presurgical, immediately postsurgical, and short-term and long-term postsurgical radiographs. The results demonstrated that presurgical mandibular morphology was not significantly different from that of control samples derived from the literature. The presurgical mandibular plane-hyoid measurement was an average of 11.4 mm greater than that in matched controls. On average, surgery resulted in a significantly longer mandible, a greater gonial angle, and a reduced mandibular plane-hyoid distance, although the response of the hyoid was quite variable. The surgical changes in mandibular length were relatively stable over the long-term. Obstructive sleep apnea did not appear to be related to abnormal presurgical mandibular morphology in this sample.